Crystal pickup unit



March 9, 1943. R. DALLY CRYSTAL PICK-UP UNIT Original Filed June 5, 19402 sheets-Shasta Q23 1/ I 28 g l' ,1 2 66 f A :4

Z W 27 ,flfg lg JIM Patented Mar. 9,

CRYSTAL PICKUP Um'r Roy Dally, Racine, Wis., assignor to WebsterElectric Company,. Racine, Wis., a corporation of Delaware Originalapplication June 3, 1940, I Serial No.

338,519, now Patent No. 2,261,616, dated Novemher 4, 1941. Divided andthis be! 3, 1941, Serial No. 413,389

application Octo- 4 Claims. (Cl; its-100.41)

The present invention relates to pick-up units for tone arms andthelike, and is particularly concerned with improved pick-ups oi thecrystal type.

This application is a division of my prior ap-- plication Serial No.338,519, filed June 3, 1940, for Crystal pick-up units.

One of the objects of the invention is the provision of an improvedpick-up structure in which the crystal is protected by special provisionfor preventing excessive longitudinal movement orv twisting movement ofthe chuck.

Another object of the invention is the provision of an improved crystalpickup unit with means for assuring the accurate location of stops oneach side of the chuck in order to prevent excessive displacement of thechuck which might cause breakage of the crystal element.

Another object of the invention is an improved adjustable stop for thechuck for a crystal pickup'unit which is adapted to permit theadjustment of the chuck stops to compensate for diameter toleranceswhich are necessary in the die-cast chuck.

Another object of the invention is the provision of an improved crystalpick-up unit which may be manufactured very economically and which maythus be placed within the means of a larger number of purchasers.

Another object of the invention is the provision of an improved housingfor crystal units of the class described, in which the connectors forconnecting the crystal unit in circuit are suitably anchored in thehousing by an improved structure.

Other objects and advantages of the invention will be apparent from thefollowing description and the accompanying drawings, in which similarcharacters of reference indicate similar parts throughout the severalviews.

Referring to the two sheets of drawings accompanying the specification:

Figure 1 is a top plan view of a phonograph equipped with a pick-upconstructed according to the invention;

Figure 2 is an enlarged horizontal sectional view taken through thepick-up with the chuck shown in elevation and taken on the line 2-2 a ofFigure 5, looking in the direction of the arrows;

Figure 3 is another enlarged vertical sectional view taken on the planeof the line 3-3 of Figure 2 looking in the direction of the arrows;

Figure 4 is a bottom plan view of a crystal pick-up embodying theinvention;

Figure 51s a vertical sectional view taken on the direction of thearrows;

Figure 6 is a rear end view of the pick-up unit; and

Figure 7 is a top plan view of the pick-up unit.

Referring to Figure 1, l0 indicates a support such as the top table of aphonograph housing which may be provided with arotatable turntable IIcarrying a record l2. The support l0 carries a standard l3 whichsupports a tone arm "It for substantially universal movement so that thetone arm can be lifted from the record and so that it may traverse therecord as it follows the needle groove.

The arm' M may be a'stamped sheet metal member of channel shape closedat each end and it may support the crystal unit or cartridge l5 at suchan angle that substantially tangential tracking of the needle can besecured at a point midway between the innermost and outermost grooves ofthe record.

The pick-up unit l5 may be supported to an arm i l by suitablesupporting angles which are secured to a supporting flange i6 that isprovided with apertures H for screw bolts or other securing devices.

The pick-up unit I5 is preferably housed in a stamped sheet metalhousing indicated in its entirety by the numeral I8. This housing mayconsist of a lower housing member I 9 and an upper housing member 20,either one of which may carry the supporting flange I6.

The two housing members l9 and 20 may be identical in shape andstructure except for the fact that one of these housing members carriesthe laterally projecting supporting flange l6 and the lowermost of thesehousing members is provided with an aperture 2| (Fig. 3) for the needlechuck.

In some embodiments of the invention, both the upper and lower housingmembers may be of similar shape and the supporting flange lt'may beeliminated. Each of these housing members is preferably formed at itsends with the relatively flat attaching flange portions 22, 23, at theleft end in Figure 2, and 24 at the right end.

The attaching flange portion 24 is located between a pair oflongitudinally extending grooves 25, 26 pressed in the housing memberand extending from the outside to the inside. These grooves are for thereception of the insulated conductors 21, 28 which lead to theconductors on the opposite sides of crystals inside the cartridge.

The conductors are for the purpose of impressing the electromotiveforces generated by the crystal upon an amplifying system.

The conductors 21, 28 are preferably rubber covered conductors having alive resilient rubber covering of circular cross-section which isslightly larger than the aperture made by the two opposed grooves 25,26. Thus the rubber covered conductors may be clamped in the grooves bythe two half-portions of the housing when the housing is assembled andthis end of the housing is sealed against moisture.

For the purpose of assuring the securement of the conductors 21, 28 inthe grooves 25, 25, one of each of the grooved housing members may beprovided with a transverse ridge or deformation which makes a slightridge 9l on the inside of each of these two grooves. This ridge 9|further clamps the rubber covered conductors and serves as an anchor.

The ends of the conductors may be directly connected to the foil on thecrystals, thus eliminating any necessity for any crystal unit. Each unitmay be provided with conductors-of suflicient length for connection toother apparatus.

The attaching flange portions 22 and 23 are in the same plane as thepart 24 and, comprise substantially'flat portions of the housing memberwhich are located on the opposite sides of pressed,

partially cylindrical groove 29 formed in this end of each housing andextending from the outside to the interior of the housing.

The groove 29 is for the purpose of receiving a rubber bearing 30 for achuck trunnion 3|, the rubber bearing 30 being in the form of a tubularresilient rubber member fitting in the groove after it has been appliedto the cylindrical chuck trunnion 3|. The trunnion and bearing assembly30, 3|, is preferably slightly larger than the groove 29 so that whenthe housing members are assembled to form a bearing aperture at 29, theycompress the rubber 30.

The housing members l9 and 29 are preferably formed with'what may betermed a plurality of separate chambers 32, 33, 34. Actually, thesechambers are in the form of a plurality of substantially rectangularpan-shaped impressions in the housing in which they are formed for apurpose further to be described.

At the outer edge of each housing member adjacent the open side, thehousing is provided with an outwardly extending lip 35, the outermostsurface 35 of which is located in the same plane as the attachingflanges 22, 23, 24. This lip is of course not necessary where thesupporting flange I6 is located, as that flange serves the same purpose.a

For the purpose of permitting a wider angular adjustment of thecartridge l inside a tone arm [4, one end of the otherwise substantiallyrectangular supporting flange IB is beveled off at 31, Fig. 1. When thetwo housing members are secured together, as shown in Fig. 5, the lips35 -on one side, and the lip 35 and flange IS on the other side engageeach other and the attaching flange portions 23, 24 engage the sameflange portions on the other housing member in such manner that thehousing is completely closed except for connectors on the the conductorgrooves 25, 26 and the bearing V groove 29. These are of course closedby the rubber insulated conductors placed in them and by the rubbercovered trunnion 3|.

The two housing members are also formed with the diagonally inwardlyextending flanges 39, 39 which are joined along aridge 40 except at apoint midway between the sides of the cartridge where this ridge 49 andthe flanges 38, 39 are varied in shape to form a partially cylindricalgroove 41 extending axially of the cartridge. The partially cylindricalgrooves 4| in the two housing members form a substantially cylindricalaperture between the chambers 32 and 33 except for the fact that the tworidges 40 do not contact each other internally and the cylindricalopening is not completely defined.

The partially cylindrical surface 4|, however, in each cartridge formssufficient of a cylindrical bearing to receive a cylindrical bearingportion 42 on the needle chuck 43 when this bearing is covered with atubular rubber member 44.

The housing members are also provided with inwardly extending flangeportions 45, 45 and the flat portion 41 which is spaced inwardly of theupper and lower walls 49, 49 in such manner that flat clamping surface50 is provided on each housing member. These, flat clamping surfaces 50are parallel to each other and parallel to the crystals 5 I, 52 and thecrystals 5|, 52 are clamped by these surfaces through the agency of theflat resilient deformable clamping blocks 53, 54.

These blocks may be made of rubber or other suitable live resilientmaterial such. as printers roll composition, and the blocks are securedto the clamping surfaces 50 by suitable rubber cement.

The chamber 34 serves as a connection chamber for connecting theconductors 21, 28 to the conducting layers 55, 55, 51 which are outsideof and interposed between the crystals 5|, 52.

As the crystal members in the present pick-up unit are disposed in aplane parallel to the plane of the record, they will of course be cutappropriately with respect to the axes of the crystal from which theyare made, so that the twisting action of the chuck under the influenceof the needle will generate electromotive forces that are collected bymeans of the conductors 55, 56, 51, and transmitted through conductors21, 28. The conductors 55, 55, 51, may be connected in various ways,such as series or parallel, as disclosed in my prior Patent No.2,145,389 of January 31, 1939, according to the characteristics desired.

The crystal member assembly 5|, 52, 55-51, is clamped at its right endbetween the resilient blocks 53, 54 which are compressed against thecrystal assembly by the clamping surfaces 59 of the housings when theyare assembled. The size of the resilient blocks 53 and 54 is such thatthese blocks are suitably compressed when the halves of the housing areassembled as shown in Figure 3. The characteristics of the crystal unitmay be predetermined by suitable compression of the resilient blocks 53and 54.

The other end of the crystal assembly is covered by a strip 60 ofliveresilient rubber or printers roll composition of sufficient width toextend be yond the borders of the clamping jaws 6|, 62 of the chuckunit'and of sufficient length so that it may be folded to substantiallyU-shape about the end of the crystal assembly and interposed between thejaws 69, 62,'and the crystal assembly.

This resilient cushion between the chuck and the crystal assembly isadapted to give predetermined cushioning connection between the crystalassembly and the chuck. The rubber strip 501s compressed and clampedbetween the opposed jaws il, 62. The pressure placed upon the crystalassembly and rubber strip 50 can be varied or adjusted by theapplication of pressure to the jaws BI, 52 to bend them into closerengageaaraaae I the rubber striped and crystalas- 4 sembly.

ment with The chuck unit 43 preferably comprises a die- ,castmetal-member which is provided with a substantially cylindrical trunnion43 at its outer end, acylindricaltrunnion c2 and the clamping jaws Thetrunnion 63 is provided with an axially extending threaded aperture '53for receiving the threaded shank 84 of a needlescrew 55 having knurledhead 56. I

Threaded aperture $3 communicates with a needle socket aperture 6'5which is also cylindrical and which is located in a diagonally'downwardand forward needle supporting lug as. The needle supporting lug 68 alsoextends upward slightly at 69 for the purpose of providing sumcient bodyfor the needle socket $1 to communicate with the bore 63 in order thatthe needle screw 65 may clamp against the needle 10.

The diagonally foward slant of the needle lug $8 and socket 6! is suchthat it gives the needle a suitable tracking characteristic. That is,the needle is disposed at an obtuse angle to the record, extendingbackward from the direction of movement. of the record so that it maymove along the groove without so much of a tendency to cut in thegroove.

The chuck 43 is also provided with a collar ll of larger size than thetrunnion 42 and with a frusto-conical portion I2 between the collar Hand trunnion 42. conical portion 13 between the trunnion 42 and theclamping flanges GI and 62. The groove or aperture 14 between theclamping flanges 6i and. 62 is preferably of substantially U-shapeconforming substantially to the curvature of the rubber strip 60 exceptthat there is a flat rectangular clamping surface 15 on each side ofeach clamping flange ti and 62 and there is a suitable clearance at 26over the rest of the groove The housing is also provided with innerdiagonally extending surfaces at each end of the cylindrical aperture 4|as indicated at ll. One element of these diagonal surfaces is in thesame location as a frusto-conical surface would be. In

some embodiments of the invention, complete frusto-conical surfacesmight be provided on both ends of the bearing 4 l, but the diagonallyextending surfaces may perform the same function in simpler embodimentsof the invention.

The rubber sleeve 64 of live resilient rubber isof such size that itextends over the cylindrical trunnion s2 and frusto-conical surfaces 12,13,

and by virtue of its tension, conforms itself to these surfaces. Theassembly of the trunnion :32 and rubber sleeve 44 is slightly largerthan the aperture 4| in which this trunnion is to be mounted.Consequently the rubber sleeve 44 is compressed and engaged at each endof the trunnion between the surfaces I7, 13 and l2, 13.

These surfaces act as thrust surfaces for preventing axial shift of thechuck and the resiliency of the rubber sleeve returns the chuck to itsoriginal position after any blow or shock. The amount of compressionplaced on the rubber sleeve 44, as well as the blocks 53, 54, rubbercushion 60 and rubber sleeve 30, is predetermined for the purpose ofsecuring the most desirable characteristics in the pick-up unit.

The two halves of the housing may be secured together by bolts and nutsor any convenient fastening means, but are preferably permanently Italso has another frusto-' a plurality of tubular rivets 13 passingthrough aperture ld in'the attaching flanges 22, 23 and j 24, and spunor riveted over-on each side-of the flanges. v I

The unit is also preferably providedwith means for providinganadjustable stop limiting the mo tion of-the'chuck t3 and thisadjustable mem--- ber 80 may be located on the lower face at of thelower housing member and secured in place bye pair of screw bolts 82which are threaded I into threaded bores-in thelower housing. This stopmember 88'- maycomprise a small sheet metal I member provided with apair of enlarged apertures as for reception of the screw bolts 32.

The enlarged apertures permit the lateral movement of the stop member-80on the screw bolts 82 until they are driven home. The stop member 90 maybe a strip of metal having a pair of laterally projecting legs 84separated by a substantially U-shaped notch or groove 85.

The inner surface of the notch or groove acts as a stop surface for thedepending lug 68 of the chuck 43. The boundary 85 of the notch acts tolimit the effective size of aperture 2| in secured together with theserubber parts in a the lower side of the housing and this stop memberdefinitely limits the amount of lateral displacement of the reproducingstylus.

By means of this adjustable plate, it is possible to provide accuratestops on each side of the chuck to prevent excessive displacement whichin turn would readily cause breakage of the crystal element. The plateis preferably adjusted after the entire crystal cartridge assembly hasbeen made and after the chuck assembly has taken its natural positionwith respect to the strain that is set up inside the assembly and by thecompression that is placed upon the rubber and other components.

The notch may be beveled at 86 to correspond in slant at its rearsurface to the surface of the depending 111g 68 in some embodiments ofthe invention.

sive lateral displacement in any of three direc tions. In the otherdirection the edge surface 81 of the aperture 2! at the front may bemade to serve as a stop surface.

In addition to the rubber elements previously described, the unit isalso preferably provided with an additional rubber block 90 which isrectangular in plan and elevation and which is compressed between thelower flange 62 of the chuck and the lower wall 49 of the housing.

This block may be made of rubber or printers roll composition and bymeans of it the resilient torsional characteristics of the assembly. aremodified and altered so as to eliminate some undesirablecharacteristics. This block is also compressed when the unit isassembled and it is secured by cement to the lower housing half. It ispreferably of sufficient the full width of the flange 62.

It should also be noted that the thrust surfaces 13, 11, 14, 11 on thechuck may also be located at some other ing 30 in other embodiments ofthe invention.

It will thus be observed that I have invented an improved crystal unitcartridge which is adapted to be manufactured very economically lengthto engage over hearing such as the bearbecadse most of its parts aremade by stamping operations and there is a minimum amount of machiningnecessary on any part of the unit. The chucks are die-cast and the unitrequires a minimum amount of rubber in its manufacture.

The needle chuck is protected against excessive lateral displacement bypositive metallic stops and it is protected against longitudinaldisplacement, such as might change its characteristics or damage thecrystal, by a resilient rubber bearing having thrust surfaces. Thepresent structure protects the crystal element against breakage bypressure or sharp blows on the chuck or needle and the present crystalunit is adapted to give faithful reproduction although it may bemanufactured in large quantities at a very low cost.

While I have illustrated a preferred embo'di ment of my invention, manymodifications may be made without departing from the spirit of theinvention, and I do not-wish to be limited to the precise details ofconstruction set forth, but desire to avail myself of all changes withinthe scope of the appended claims.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States, is:

1. In a crystal cartridge unit the combination of a housing of rigidmaterial with a crystal secured in said housing and having one end 2. Ina crystal cartridge unit the combination of a housing of rigid materialwith a crystal secured in said housing and having one end clamped bylive resilient non-metallic cushions interposed between both sides ofthe crystal and the housing, a chuck connected to said crystal dependingtherefrom and extending through an aperture in said housing, andadjustable stop means located at said aperture, said stop means beingadjustable after the unit has been completed for the purpose of limitinglateral displacement of the chuck beyond a predetermined point, saidstop means comprising a metal plate having a notch surrounding saidsocket member.

3. In a crystal cartridge unit the combination of a housing of rigidmaterial with a crystal secured in said housing and having one endclamped by live resilient non-metallic cushions interposed between bothsides of the crystal and the housing, a chuck connected to said crystaland movably supported in said housing, said chuck having aneedle-supporting socket member depending therefrom and extendingthrough an aperture in said housing. and adjustable stop means locatedat said aperture, said stop means being adjustable after the unit hasbeen completed for the purpose of limiting lateral displacement of thechuck beyond a predetermined point, said stop means comprising a metalplate having a notch surrounding said socket member, said metal platehaving enlarged apertures and threaded means passing through saidapertures and threaded into said housing for clamping the plate in anyof a plurality ofxiitlerent positions.

' clamped by live resilient non-metallic cushions 4. In a crystal unit,the combination of a pair of metallic housing members of substantiallysimilar shape except that one of said housing members is provided with aneedle aperture, each housing member being provided with a border rimfor engaging the border rim on the other housing to effect a closure atthe edges of the housing members and each housing member being' providedwith a plurality of flat attaching flanges located at the ends thereof,a crystal unit assembly in said housing including a crystal secured to achuck, said chuck having tbearings. resilient means interposed betweensaid assembly and said housing and brought into resilient clampingengagement with said assembly when the housing is assembled, andadditional resilient and movably supported in said housing, said chuckhaving a needle-supporting socket member ,meansclamped between thehousing and a part of said chuck for adjusting theresilientrcharacteristics of the crystal assembly by effecting a dampingaction between a flat side of said chuck and a flat part on saidhousing.

' ROY DALLY.

